The results of a combined analytical and experimental investigation of the unbalance vibrations of a rotor are presented. The analysis applies to a general rotor-bearing system in which the dynamic bearing forces are represented by four spring coefficients and four damping coefficients. The rotor can be represented as either a lumped or a distributed parameter system, and gyroscopic moments are included. In general, the unbalance whirl motion of the rotor will be elliptical. The analysis has been programmed for a digital computer to obtain results for comparison with the experimental data. The test rotor is a uniform, flexible shaft with heavy wheels mounted at the ends and in the middle. The rotor is supported in two silicone fluid-lubricated, tilting-pad bearings. The rotor amplitude caused by an induced unbalance has been measured over a speed range of 3000 to 24,000 rpm for three different rotor configurations, obtained by removing one or both end wheels. This speed range extends to or through the third critical speed for each of the rotor configurations. The results are compared with the theoretical values and, in general, the agreement is found to be good.
Calculated data on steady-state and dynamic properties of the plain cylindrical floating-ring bearing with pressurized lubricant supply are given. The data are for a bearing with L/D of 1, and values of the ratio of inner to outer film clearances of 0.7 and 1.3. One value of dimensionless supply pressure parameter is covered. Experimental results are presented which verify the calculated results and which supplement them, particularly with respect to stability characteristics of the bearing.
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